Last week I plugged an SSD with a bootable APFS volume with macOS into the USB port of a Macbook Pro 2010. It wasn’t seen in startup manager, as I had suspected. This macbook had never been used as it had been stored in an exposition, so its firmware had never been updated. It had its original and never used macOS 10.6 Snow Leopard installed.
Please correct me if this assumption is not correct:
Any mac whose firmware was never updated after APFS was first launched by Apple won’t see APFS volumes in startup manager because the logic board firmware wouldn’t be able to read APFS. If any mac with installed macOS releases such as Yosemite, El Cap, Sierra can see a bootable APFS volume in startup manager, it’s because it’s firmware has been updated to be able to read and write APFS. Is this correct??? The 2010 macbook mentioned above admits macOS up to the latest release (now High Sierra).
Any clarification much welcome.